Dinosaurs, amazing fossil collections, field reports, research news, historical photos and more from the Department of Paleobiology at the Smithsonian National Museum of Natural History.

07/30/2015

Antoine Bercovici is a Peter Buck postodoctoral fellow in the Department of Paleobiology at the National Museum of Natural History. He has been in the field since early July, and sent this post from North Dakota.

During the past two summers, members of the Department of Paleobiology conducted fieldwork in the badlands of North Dakota and Montana. They were collecting fossils for the Last American Dinosaurs Exhibit and contributing to decades of research aimed at unlocking the secrets of an ancient ecosystem. This ecosystem, known as the Hell Creek after the fossil rich rock formation that formed here at the very end of the Cretaceous period, saw the iconic battle of the mighty Tyrannosaurus rex and Triceratops. But it was not just dinosaurs that lived there: many smaller animals thrived in this ecosystem, including crocodiles, turtles, lizards, salamanders, snakes, birds, fishes, and small mammals. They were living in a very lush world, comparable to today's Everglades, as indicated by the very diverse plant fossils also found in the rocks. This world came to an end 66.043 million years ago, as a giant asteroid hit the Earth in what is now the Yucatan Peninsula. The environmental disaster that followed caused many of the Hell Creek species to go extinct — most notably, the non-avian dinosaurs.

The North Dakota badlands show different layers of colored rocks. A major change in deposition can be seen here, indicated by the arrow: below are grey and monotonous sediments of the Hell Creek Formation, and above are the multi-colored sediments of the Fort Union Formation. Click to zoom.

This summer, our team is collecting new data that will tell us how stable the Hell Creek ecosystem was prior to the asteroid impact. We want to know how abundant the last dinosaurs inhabiting this part of North America were, and how their populations were changing over time. In order to answer these questions, we need to be able to place the fossils discovered here on an extremely accurate timeline. In geology, time is represented by the deposition of layers of sediments that accumulate on top of each other like a stack of pancakes: the deeper you go, the older the sediments and the fossils they contain. We are building our timeline by recording the elevations of Hell Creek fossil discoveries relative to the top of the Hell Creek Formation (the top of the pancake stack).

The mapping team is composed of Kirk Johnson, Sant Director of the National Museum of Natural History; Tyler Lyson, Curator of vertebrate Paleontology at the Denver Museum of Nature and Science; Gabi Rossetto, also from the Denver Museum of Nature and Science; Erica Evans of Colorado College; Dean Pearson of the Pioneer Trails Regional Museum in Bowman North Dakota; and myself. This mission involved a trip down memory lane as we pulled out old field notebooks to re-locate close to a thousand fossil sites that were discovered during the past thirty years of work in the Hell Creek of North Dakota. Walking back to every single site, we are marking their geographical positions with a Global Positioning System (GPS) unit and, more importantly, measuring their precise elevations.

Erica Evans (top), Tyler Lyson (right) and I point at a very distinctive white layer of sediment just above the Hell Creek - Fort Union formation contact. This layer marks the end of the Cretaceous and the demise of the non-avian dinosaurs; it is composed of material ejected from the crater that formed as an asteroid struck the Earth about 66 million years ago. We are using the GPS unit that Erica holds to measure the elevations of all our fossil sites relative to this layer. Click to zoom.

The GPS technology, developed and maintained by the US Army, is capable of incredible accuracy. In military use, it measures positions down to the nearest centimeter (cm). The system available to civilians, however, has a degraded resolution, with elevations typically measured only to within 10 meters (m), which is too much uncertainty to be useful for our project. (The Hell Creek Formation is about 100 m thick, so a 10 m error represents a 10% uncertainty in the position of a fossil site.) To get the accuracy needed for our project, we are using a technique called differential GPS, where we compare the readings of two GPS units to reduce the error. Every day, we set up a fixed GPS base station that records position and drift for several hours. We then map our sites using a mobile GPS unit that we carry with us. In the evening, the data recorded from both GPS units are downloaded to a computer, where dedicated software computes a correction, bringing the error at each site down to about 10 cm.

(Left) Erica Evans and Tyler Lyson setting up the GPS base station, nicknamed "The Brain,” early in the day. It will record the drift of the GPS position for a fixed point during several hours, allowing us to increase the accuracy of our field measurements. (Right) Erica Evans recording the position of a hadrosaur (duckbill dinosaur) rib that is eroding out of the hill. Click to zoom.

Our timeline fills with more and more fossil sites with each passing day of fieldwork. As we get a better idea of the distribution of our sites in time, we see gaps that we were not aware of before. Fortunately, the data also direct us to areas where we should prospect for new fossils that will fill the timeline gaps! Ultimately, we will have a very good understanding of how the fossils of dinosaurs and other animals are spread out in the 100 m thick Hell Creek Formation, and how ecosystems may have changed in the 1.3 last million years of the Cretaceous, before the asteroid impact.

So much ground to cover. Where should we go next? So far, we have visited about 300 fossil sites in an area of approximately 1000 square kilometers. Click to zoom.

Photos by Antoine Bercovici.

View earlier posts about Department of Paleobiology fieldwork in the Hell Creek Formation in 2013 and 2014.

07/17/2015

James Williams Gidley (1866-1931) was a vertebrate paleontologist at the United States National Museum (USNM), the forerunner of the National Museum of Natural History, during the early 20th Century. He was both a skilled fossil preparator and an active researcher, and his accomplishments in both areas are still felt within the Museum’s exhibits and collections. His career is described in a new essay by Department of Paleobiology volunteer Mark Lay, which was adapted for this post.

Dr. Gidley led or co-led approximately 20 field expeditions from the Museum to locations as far flung as Maryland, Montana, Indiana, Nebraska, Arizona, Oklahoma, and Florida. One of the most important was his collection and study of Pleistocene mammals from Cumberland, Maryland.

As the Western Maryland Railroad Company expanded its line west in 1912, workers exposed a small cave system while cutting through limestone rock on the side of Wills Mountain near Cumberland, Maryland. A local resident and amateur fossil collector, Raymond Armbruster, noticed that workmen were carrying fossil bones from the cave as curiosities, and sent a small sample to the USNM for examination. While caves are relatively common, caves containing fossils are not, so Dr. Gidley planned a trip to the site in October 1912. This initial trip resulted in the collection of more than 100 specimens, mostly jaws and jaw fragments from at least 29 different species of mammals, most of which are now extinct. This success was encouraging enough that Gidley and Armbruster collected sporadically at the site for another three years.

The Cumberland Cave in Maryland, circa 1913. The photo on the lefts shows the cave entrance, dwarfed by the size of the railroad cut. A tarp and wooden beams mark the opening, which is just left of center in the photo, at the level of the railroad tracks. In the photo on the right, James Gidley stands just outside the cave entrance. Photos by R. Armbruster. Click to zoom.

Although the limestone of Wills Mountain is of Devonian age, all the specimens collected from the cave and identified by Gidley are of Pleistocene age, suggesting that, roughly 200,000 years ago, the cave system was connected to the surface for a time by a sinkhole. Based on the probable topography, the sinkhole was approximately 100 feet deep, making it likely that anything that fell in would remain there. The fossils found are a mixture of animals that may have lived in the caves (such as bats, owls and invertebrates), some that may have fallen in, including terrestrial vertebrates (such as wolverines, bears, and peccaries), and numerous plants, all encased in sediments washed in over the years.

Several exhibit mounts were made from Gidley's Cumberland Cave fossils. The black bear and wolverine shown below were exhibited in the Ice Ages Hall until recently.

These mounts are relatively small in size, but Dr. Gidley’s overall impact on exhibits was huge – literally. He supervised the mounting of a whale, Basilosaurus cetoides, the “Indiana Mastodon,” and a large titanothere, Megacerops coloradensis.

Basilosaurus cetoides

Basilosaurus is a genus of Eocene whales that lived about 35-40 million years ago. Our specimen of Basilosaurus cetoides (USNM 4675) is a composite made from the skull and skeletal elements of three individuals collected by Charles Schuchert (Assistant Curator of Invertebrate Paleontology in the USNM) in Alabama in 1894 and 1896. At first, no attempt was made to reassemble the skeleton into a life-like pose, but after Frederic Lucas (Curator in the Division of Comparative Anatomy in the USNM) published a partial description of the whale’s anatomy in 1901 it became possible to consider creating a true restoration. Dr. Gidley was responsible for directing the creation of the mounted specimen, and the work was completed in 1912. This was the first mount of a Basilosaurus ever done. It measured in at approximately 55 feet long and was given a prime spot, shown below, in the Hall of Extinct Monsters.

Gidley's mount of Basilosaurus cetoides (USNM 4675) as it was first displayed in the Hall of Extinct Monsters. Photo courtesy of Smithsonian Archives. Click to zoom.

The mount survived essentially “as is” until 1989, when it was given some anatomical corrections and repairs and moved into the “Life in the Ancient Seas” exhibit (below, left). Then, in 2008, it was remounted in a new pose on a modern armature. The hind limbs were replaced with cast bones from another specimen, and the skeleton was moved to the Sant Ocean Hall (below, right), where it can be seen today. It remains the only real mounted Basilosaurus specimen on display in the world.

Photos by Chip Clark. Click to zoom.

Indiana Mastodon

Most of the American mastodons (Mammut americanum) found in this country are fragmentary. Complete (or relatively complete) skulls and skeletons are rare. One of those rare finds was reported to the USNM in 1914. On October 30th, George P. Merrill, Head Curator of Geology, wrote to the Assistant Secretary that “Mr. W. D. Pattison, a druggist of Winamac, Indiana, called at the office a few days ago and stated that in the work of ditching on some of his property in Indiana they had found a Mastodon skeleton, evidently in a good state of preservation; that they had removed only portions of the skull and one limb bone, which they would donate to us if we wished, and also give us the privilege of exhuming the entire skeleton.” The Museum paid for the bones to be shipped to Washington, where James Gidley examined them. Gidley reported to Merrill that, “the specimen… consist(s) of finely preserved portions of… an unusually large individual and with a minimum amount of preparation would make an attractive exhibit.” He went on to describe where a mount of such size could fit within the existing exhibit hall, concluding, “If, therefore, funds should become available at any time in the reasonably near future, I believe it would be well worth while accepting Mr. Pattison’s offer to exhume the remaining parts.” Funds must have been forthcoming because Gidley made two trips in 1915 to excavate and remove the rest of the specimen. The nearly complete skeleton (USNM 8204) required only limited restoration (done under Gidley’s direction) and the mount was put on display in 1916.

James Gidley stands with the newly mounted "Indiana Mastodon" (Mammut americanum, USNM 8204) in the Hall of Extinct Monsters. Click to zoom.

Megacerops coloradensis

A photograph (below) from our archives suggests that Gidley also supervised the creation of a third large display mount, that of Megacerops coloradensis (USNM 4262, this specimen had been excavated in Nebraska by John Bell Hatcher in 1887 and identified previously as Brontotherium hatcheri.) Dated 1919, the photo shows Gidley posed at the head of the mount with a sketch of the animal in his hands. Two men in work aprons, presumably Thomas Horne, who is known to have built the mount, and a helper, believed to be John Barrett, stand to either side of the skeleton. The Museums Annual Report of 1920 trumpeted both the skill involved in creating the mount and that, “this imposing addition [to the exhibits] … is the first and only mount to the genus to be exhibited.”

At work on the mount of Megacerops coloradensis (USNM 4262), a large Eocene herbivore. Click to zoom.

The Museum has always been justifiably proud of the many unique fossil specimens exhibited in its halls, and through the work of Gidley and others during the early decades of the 20th Century the number of these important mounts rose substantially. But with time they have become outdated. The mastodon and Megacerops, along with many other exhibit specimens, were disassembled recently as part of our ongoing National Fossil Hall renovations. After their bones have been conserved, they will be remounted on modern armatures and positioned in new stances that reflect 100 years of advancement in our scientific understanding of how these animals stood and moved. We have no doubt that James Gidley would approve of these changes to his century-old work.

Read more about the history of the Department of Paleobiology at the National Museum of Natural History, our collections and exhibits here.

06/15/2015

It's been just over a year since the National Fossil Halls closed for renovation, and we've reached an important landmark; the last fossils have been taken out of the exhibit, and numerous models, dioramas and paintings have been removed as well. Demolition is under way.

The final dinosaur specimens to exit the halls were the tail and hind limbs of Corythosaurus casuarius (USNM 15493) and the full skeleton of Ceratosaurus nasicornis (USNM 4735). Both had been exhibited on the wall as "plaque mounts," with most of the bones partly embedded in plaster. Neither was small enough to pass out of the exhibit intact.

The plaque mount of Corythosaurus before it was removed from the wall.

Sheathed in plywood to protect the fossil from overhead work, the frame holding the Corythosaurus was detached from the wall and lifted onto the floor.

Preparator Matthew Miller split the plaque carefully, separating the front of the specimen from the back. The halves were small enough to move into storage.

This 1920 drawing from a scientific publication by Charles W. Gilmore shows the reconstructed skeleton of Ceratosaurus as it was positioned for display. The mount was first exhibited in 1910.

Preparator Deborah Wagner freed the skeleton of Ceratosaurus from the plaque in sections.

The empty plaque after the framework was cut and chunks of skeleton were extracted from the plaster.

Specimens of Ceratosaurus are rare, and ours, found in the 1880s, was the first discovered. Because of its scientific and historical importance, we will preserve the original bones in our collections and make casts (exact replicas) from them for exhibit in the renovated Fossil Halls. Stay tuned for future posts about molding and casting the individual bones and building the new skeletal mount.

The last mammals to leave the Fossil Halls were Harlan's ground sloth, Paramylodon harlani (USNM 15164), and the Stegomastodonarizonae (USNM 10707). These large specimens are rotating out of the exhibit lineup and entering storage, where they will be available for scientific study. But first they must be conserved and dismantled, and appropriate archival storage jackets and trays must be built for all of the bones.

Before the Stegomastodon could be moved, the surrounding exhibit flooring had to be pried away. A dusty job.

Taking off the ribs. Too large to fit in the elevator, the skeleton was partly dismantled before removal from the exhibit halls.

Many hands make less-heavy work. The Harlan's ground sloth was just small enough to fit through all the doorways between the exhibit and the lab where it would be dismantled.

The sloth's arm and hand bones are shown in the new archival storage we are creating for specimens not returning to the renovated exhibit.

Preparator Alan Zdinak sets up to build a storage jacket for the ground sloth's pelvis. Read more about storage jackets in an earlier post.

Fossils weren't the only things that needed to make way for the renovation. The photo below shows the removal of one of many paintings from the exhibit.

A team of art conservators peels a mural off the wall in the Ice Ages Hall. This 1975 painting on canvas by paleoartist Jay Matternes depicts life on the tundra during the Pleistocene. It is part of a set of Matternes' murals that will be conserved and held in our collections for future use.

We are keeping many of the models that helped bring the Fossil Halls to life for our visitors, but some models have been given to other museums. The life-sized models of the pterosaur Quetzalcoatlus (shown below) and Stegosaurus, for example, were trucked to the Museum of the Earth in Ithaca, New York. These models, too, had to be cut into pieces to fit through the doors, so they will have to be reassembled before they can be exhibited.

Quetzalcoatlus, as most visitors saw it, high in the air above the dinosaurs.

Its head, up close, upside down, and packed for transit.

Read earlier posts about dismantling the Fossil Halls here. Future posts in this renovation series will include highlights of our work on specimens returning to exhibit in 2019.

05/01/2015

One of the National Museum of Natural History's responsibilities as a repository for the National Fossil Collections is ensuring that the fossils are preserved, in excellent condition, for future scientific study. But without special care, fossils tend to break over time. Not only are there stresses from being picked up and moved around, but gravity takes a natural toll on heavy, rigid, irregularly shaped objects such as fossils. An earlier post described our work in FossiLab to rehouse our fossil crocodilians in supportive storage trays designed to reduce such damage. Last month, the volunteers finished the crocs and began to rehouse the Museum's type collection of fossil marine mammals. "Type" collections are especially important because they include the fossils on which scientists based the naming and detailed descriptions of new species. Because subsequent discoveries must be compared to type specimens to determine if they are new to science or simply new specimens of known species, there is high demand for access to type collections. This increases both the potential for damage from "wear and tear" and the need to keep the specimens in excellent repair. The photos in this post show some our strategies for achieving both goals. Click photos to zoom.

The lower jaw of a primitive dolphin, Simocetus rayi (USNM 256517), shown above, left, is about 30 million years old. In its new tray, the bone makes contact with the foam beneath it, but the delicate teeth rest on a pillow of batting. This prevents the teeth from shouldering any of the weight of the surrounding bone and reduces the chance they will break. The finger-sized cutouts to the left guide researchers wishing to lift the jaw to grasp it at a safe distance from the teeth. We incorporate "behavior guides" like this into the housing for most specimens. Even the robust vertebra, shown above right, from Basilotritus wardii (USNM 310633), a primitive whale, could be damaged if picked up by the relatively delicate transverse processes (the winglike structures extending from the left and right sides), so we guide the hands elsewhere.

Above left, a volunteer compares bones from the shark toothed dolphin Squalodon whitmorei (USNM 183023) to the photos in the scientific article in which it originally was described. Checking the bones against the illustrations lets us know if any of them have broken during their years in storage. If pieces are missing, we find and reattach them with adhesive. Specimens often include small bone fragments that were found alongside the larger bones, and we check these for pieces that go together, as well. It's surprising how often we find a match (already, through the years, the pieces have been looked over by many sets of eyes) but we are very good at jigsaw puzzles. To the right, above, repaired and rehoused vertebrae of Squalodon calvertensis (USNM 10484) are laid out neatly in a new storage tray.

While all of the fossils in the type collections are scientifically important, some of them are particularly awe inspiring. The three bones to the right are the paired pelvic bones and a femur (upper leg bone) of Basilosaurus cetoides (USNM 12261), a primitive whale that lived about 40 million years ago. Whales evolved from 4-legged animals that lived on land, and as they adapted to life in the water, their hind limbs became small and lost their original function. In the sketch below, taken from an early 20th century publication, you can see these bones in the context of the full skeleton, about half the distance between the ribs and the tip of the tail. The specimen is about 17 meters (55 feet) long, overall, but the diminutive femur measures only about 20 cm (8 inches) in length! When the rest of our skeletal mount of Basilosaurus was put on display in the Sant Ocean Hall, our scientists decided to keep these bones in the relative safety of our collections, replacing them with replicas made from the hind limbs of another specimen.

03/19/2015

We are wrapping up the removal of specimens from the Fossil Halls at the National Museum of Natural History, the first step in our massive renovation project. During the last few weeks, riggers carefully brought large fossils mounted high up on the walls back down to Earth. One of the skeletons, shown below, was from a Late Cretaceous predatory dinosaur, Gorgosaurus libratus (USNM 12814).

The photo on the left shows the mounted Gorgosaurus being lowered from its high perch. To bring it down safely, the riggers strapped the slab into a steel cradle, attached the cradle to cables strung from I-beams in the roof, and used hoists to control its descent. The skeleton (shown safely on the ground in the photo on the right) is mounted in a “death pose” with the bones arranged as if still in the ground. For many years this specimen was labeled Albertosauruslibratus because Gorgosaurus was once thought to belong to that genus. Click photos to zoom.

This fine specimen was collected in 1913 in Alberta, Canada, by Barnum Brown, a paleontologist at the American Museum of Natural History (AMNH) in New York, and came to the Smithsonian in 1933 as part of a complicated exchange of fossils. (Natural history museums have long traded “duplicate” specimens as a way of broadening their collections and fleshing out their exhibits - an earlier post on this blog describes the 1935 exchange with the Carnegie Museum of Natural History that netted the Smithsonian its Camarasaurus.) The trade for the Gorgosaurus had its root in an attempt by the Smithsonian, in 1919, to obtain a specimen of Moropus elatus, a large herbivore that lived during the Early Miocene. The AMNH had collected enormous numbers of bones of Moropus during a decade of work at Agate Springs Ranch (now Agate Fossil Beds National Monument) in Kansas, and it was offering several exhibit-quality skeletons for sale.

This vintage photo shows a mounted skeleton of Moropus, with its characteristic long front legs and clawed toes. The Smithsonian had no specimen of this horse-sized animal, but hoped to get one in a fossil exchange with the American Museum of Natural History. Click for image source.

Having neither the cash in hand nor the hope of raising the necessary funds, James W. Gidley, of the Smithsonian’s NMNH, suggested that the skulls and jaws of several species of brontothere - another large herbivore - might serve as an even trade. AMNH researcher (and President) Henry Fairfield Osborn badly wanted several of our brontothere specimens for study and display, and Gidley had selected some excellent skulls for him.

In this 1919 photo, NMNH Assistant Curator James W. Gidley (right), and two fossil preparators stand in the preparation lab with the newly mounted skeleton of a brontothere, Brontotherium hatcheri (USNM 4262), which was placed on display here in 1920.

These photos show part of an NMNH exhibit comparing the skulls and jaws of 22 different species of brontothere. The AMNH hoped to create a similar display, but needed more specimens. Thanks to vigorous collecting in the 1880s and 1890s by John Bell Hatcher, we possessed a superabundance of brontotheres, and could offer some in trade.

The brontotheres were sent to Osborn, but Walter Granger of the AMNH informed Gidley that a skeleton of Moropus could not be sent in exchange. He wrote that any deal for Moropus must be cash only. Not only did the AMNH need to pay the landowner on whose property it had been quarrying, but it wanted to recover the cost of shipping and preparing its “duplicate” specimens. Granger applied some not-so-subtle pressure in his argument for cash, writing that the finest skeleton had been sold already to the Yale Peabody Museum of Natural History, and others had been offered for sale to two European museums. "The chances of securing new skeletons of Moropus are remote," he wrote. "There are undoubtedly more of them in the hill from which ours … came, but the cost of removing them has now become almost prohibitive because of the overburden.” (Overburden is the overlying rock matrix that must be dug through to reach a fossil-bearing layer). Gidley offered additional specimens in hopes of making an exchange more attractive, but the AMNH held firm, saying that at least some cash needed to change hands. Frustrated, Gidley wrote to AMNH curator William D. Matthew, saying, “I hope your rejection of my proposition does not mean that the deal is entirely closed, but only that it may be approached from a somewhat different angle.“

An acceptable angle wasn’t found until 1932, when the AMNH wanted to include a long-necked giant sauropod, Barosaurus, in a new exhibit on dinosaurs. The AMNH didn’t own a Barosaurus, and was ready to deal. The skeleton it hoped to acquire had been excavated from Dinosaur National Monument (the source of many sauropod skeletons) by three separate institutions working in the same quarry in successive years; some of the specimen was at the Carnegie Museum of Natural History, some was at the University of Utah, and the rest was at NMNH.

NMNH Curator Charles W. Gilmore had acquired our portion (USNM 11657) in 1924, while excavating a Diplodocus to exhibit in the Fossil Halls. The skeleton was incomplete, so Gilmore selected bones from a nearby skeleton, thought to be another Diplodocus, to fill in the gaps. When the supplemental bones turned out to be from a Barosaurus, instead, they were placed in our collections. In 1923 Osborn, of the AMNH, was tasked with trading for them. He offered the skeleton of Gorgosaurus (AMNH 5428,) or, if we preferred, a ceratopsian dinosaur. In January of 1933, he sweetened the deal, adding to the offer (finally!) a mountable skeleton of Moropus. In very short order, the Smithsonian's part of the Barosaurus was loaded into thirteen boxes and sent to New York by truck, and the Gorgosaurus and Moropus were sent in return. And what happened to the brontothere skulls sent to the AMNH fourteen years earlier? They became part of this deal, too. The AMNH got to keep them.

The skeleton of Moropus (NMNH 12816) (right) was mounted for display and installed in the Fossil Halls around 1936. Before the recent renovation work began, it was exhibited in front of a mural showing life reconstructions of many species excavated from the Agate Fossil Beds. The mural was painted by Jay Matternes in 1961 and includes two adults and a juvenile Moropus, shown in the detail on the left.

You can read earlier posts about our exhibit renovation here and learn more about the history of the Department of Paleobiology, our research and exhibits here.

02/17/2015

FossiLab has been overrun by crocs. Since November, National Museum of Natural History visitors have been watching us create archival storage for the Department of Paleobiology's extensive collection of fossil crocodilians. Ranging from individual teeth to nearly complete skeletons and in age from about 66 million to just a few million years old, the hundreds of fossils in this collection are the fruit of more than 150 years of collecting by Smithsonian staff and their professional and amateur colleagues.

Like most people, we are impressed by fossils with big teeth, but the collection contains less toothy marvels as well. Here are some highlights from our work:

This 10 million year old specimen of Gavialosuchus (USNM 24939) was found nearby in Maryland. The jaws and other skull fragments are shown resting in newly-created archival storage trays.

Sorting through drawers holding a specimen of Boverisuchus vorax (USNM 12957) collected by Charles W. Gilmore in Wyoming in 1930, we found the fragmented and incomplete skull, shown in the foreground of the photo above, left. FossiLab volunteer David Ouderkirk, right, was able to piece many of the skull fragments back together before rehousing it. Boverisuchus (formerly known as Pristichampsus) is noteworthy for its teeth, which are similar to those of predatory dinosaurs. It may have primarily been a land-dwelling predator.

One of the most historically interesting of the storage drawers contained nearly a hundred small boxes of fossils recovered by collectors for the famous 19th century paleontologist O.C. Marsh at a site called Quarry 9 at Como Bluff in Wyoming. This quarry is famous for yielding thousands of fossils of small vertebrates from the Morrison Formation (Late Jurassic), among them mammals, small dinosaurs, amphibians - and crocodilians. The pair of photos above shows the drawer before, left, and after, right, the fossils and their historic labels were cleaned and rehoused.

The crystals that fill this lovely specimen, USNM 12597, makes it appear geode-like, but microscopic analysis of the outer layer reveals structures typical of crocodilian eggshells. The egg was laid during the Eocene, about 45 million years ago, and is one of several collected in present day Wyoming in 1930.

The collection also contains some casts (exact replicas) of croc specimens, and we are improving storage for these as well. But sometimes we have a little fun with them first. The cast above is of the specimen of Gavialosuchus shown in the first photo of this post. Yes, we really are impressed by fossils with big teeth!

This work is part of a long-running effort in the Department of Paleobiology to update storage for all of our fossils. Next up for rehousing in FossiLab is the fossil marine mammal collection.

01/15/2015

The vintage painting shown below, left, was recently found rolled up in a drawer in the Department of Paleobiology’s fossil storage area. It depicts two fossil preparators working in front of the public, with reconstructions of dinosaurs depicted on the wall behind them. Enlargements on the right show two of the stylishly dressed visitors, one of the reconstructions, and a sign identifying the fossil undergoing preparation as a specimen of the Late Jurassic sauropod dinosaur Camarasaurus from Dinosaur National Monument. Everyone who saw the painting was intrigued. Was this a plan for an exhibit? Was it ever built? What could we learn about the Camarasaurus? Were the reconstructions ever made and, if they were, who did them?

It turns out that in 1936, chief fossil preparator, Norman H. Boss, was sent to Dallas as part of the Smithsonian’s participation in the Texas Centennial Exposition. Boss and a hired assistant, Gilbert F. Stucker (who later became a preparator at the American Museum of Natural History), worked in the Dallas Federal Building from June 6th through the end of November, preparing a skeleton of Camarasaurus (USNM 13786) from five large field jackets. Newly-completed 15x8' oil paintings of Camarasaurus (by R. Bruce Horsfall) and Dimetrodon (by Garnet W. Jex) in their environments, prepared under the direction of Smithsonian vertebrate paleontologist Charles Whitney Gilmore, and a diorama depicting “all known life of the Jurassic age” were also exhibited, with the intention of showing “a picturization of the scientific knowledge of prehistoric reptilian life derived from laboratory studies.” Other, non-reptilian fossils, including mammoth teeth, were displayed in cases nearby.

The Department’s archives yielded photos, below, of Boss taking hammer and chisel to one of the field jackets at the Texas Exposition. On the left, a life-size sketch of the dinosaur can be seen behind Boss, with previously-prepared skull and vertebrae mounted in front. The painting is Horsfall’s reconstruction of Camarasaurus. The photo on the right shows bones that had been removed from the rock displayed on tables, and a large, unopened field jacket on the floor.

Six million people attended the Expo. Despite competition from displays of such new wonders as television and air conditioning, the Smithsonian exhibit must have been very popular, as Boss was sent back to Dallas the following year to prepare fossils in front of crowds attending the Greater Texas & Pan American Exposition.

The museum began sending fossils to major expositions in 1895 (an earlier post describes the travels of our papier mâché Stegosaurus to the St. Louis Exposition of 1904). What was gained from participating in these events? Gilmore, in his History of the Division of Vertebrate Paleontology, wrote that not only did expositions afford opportunities to make the work of the Smithsonian known to the public, but they also provided funds for the purchase of “illustrative material” such as paintings and models, as well as new specimens. Indeed, the Texas Centennial Commission paid for the paintings, the diorama, and for several fossils Gilmore felt were of exceptional scientific importance -- although it’s not clear these fossils ever went to Texas.

In contrast, the Camarasaurus was not acquired specifically for the Texas Centennial. Beginning in the 1920s, the Carnegie Museum of Natural History in Pittsburgh had excavated numerous specimens of these large dinosaurs, along with other species, at Dinosaur National Monument in Utah. Gilmore had excavated our spectacular skeleton of Diplodocus there as well, but the Smithsonian did not have a good specimen of Camarasaurus -- and we wanted one. Fortunately, we had things the Carnegie desired, which could be offered in trade; the dinosaur expertise of Charles Gilmore and fossil horses which, thanks to several productive expeditions to Idaho in 1929 and the early ‘30s, we had in abundance. So a plan was hatched in 1933 between the Director of the Carnegie and the Assistant Secretary of the Smithsonian to trade one skeleton of Camarasaurus (valued at $6000) for 5 months of Gilmore’s time ($2080), a skeleton ($1000) and 8 skulls ($150 each) of the Pliocene horse Equus simplicidens (aka Hagerman horses) and $1720 in cash. The skeleton of Camarasaurus, “complete from the skull back to the beginning of the tail and all articulated,” was logged into the Smithsonian collections in 1935, and, made its appearance in Dallas with Norman Boss in 1936. A year later, $950 of Greater Texas and Pan American Exposition funds were used to purchase another Carnegie Camarasaurus specimen (USNM 15492), this time “a nearly complete tail… in the rock.” The tail was shipped by rail directly to Dallas on June 7th, 1937, just in time for opening of the Exposition on June 12th.

After the second Exposition wrapped up in November of 1937, the Smithsonian’s newly-acquired materials were shipped to the museum, and space was found within our exhibits for the paintings, the diorama, and, eventually, the skeleton of Camarasaurus. The photos below show, left, Garnet Jex’s reconstruction on the wall above a skeleton of Dimetrodon, and, right, the skeleton of Camarasaurus (with the 1937 tail added!) as it was displayed, until recently, in “death position."

Today, the Camarasaurus is being conserved as part of our ongoing fossil exhibit renovations. When the National Fossil Halls reopen in 2019, visitors will, for the first time, see this large skeleton mounted in a dynamic, upright pose. But they'll have to come to Washington, D.C., not Dallas, to see it!

12/19/2014

Diplodocus has left the building. Our largest dinosaur skeleton had stood in the National Museum of Natural History's Fossil Halls since 1931, delighting millions of visitors who craned their necks this way and that as they tried to take in its astonishing dimensions. Now, the bones are packed in shipping crates and on their way to the company that will build a new metal armature to support the massive skeleton. When it is reinstalled in the renovated National Fossil Halls in 2019, Diplodocus will have a new stance that reflects the latest knowledge about how these giant dinosaurs stood and moved.

The fossil was collected in Dinosaur National Monument in Utah in 1923. It took years to prepare the bones for display and build a metal armature strong enough to support them in a life-like pose. This photo shows the mount during its installation.

The mount was completed in 1931. The vertebrae rested on a heavy cast iron band held aloft by four sturdy poles. Smaller bands supporting the limbs and ribs were suspended below. Photo dates from the 1940s.

During Fossil Hall renovations in the 1960s and 1980s, Diplodocus was protected by construction barriers and draped plastic as nearby displays were expanded and rearranged, and demolition and construction took place in the surrounding spaces.

The mount protected by a construction barrier during the early 1960s.

Other dinosaur mounts were rearranged around Diplodocus during the 1960s renovation. The Triceratopsin the front left of the 1940s photo is now in the rear.

Among the 1980s changes, Triceratopsand other dinosaurs were moved again, and the floor around the central display was raised. Photo by Chip Clark

The current renovation is different. It involves such extensive infrastructure updates and exhibit reconfiguration that Diplodocus simply can't stay put. Photos from its recent "de-installation" are below.

Before: The surrounding specimens were removed and the platform was cut down to allow access for a lift and hoists.

The limb bones and ribs came off first. A hoist was needed to lower the heaviest limb bones.

Once all but the heaviest vertebrae had been removed from the armature, the platform was cut down even further.

The heavy sacrum was held aloft by a hoist as the post that once supported it was cut away.

Too heavy to move around by hand, the heavy sacrum was packed for travel by building a crate around it as it hung from the hoist.

The bones filled many crates. Each was supported by foam and secured in place with straps to prevent any movement.

In taking apart and reassembling Diplodocus and other old mounts, we have a rare opportunity to provide their bones with much-needed conservation work and to update their armatures using the latest mounting technologies. Who knows when a chance like this will come again?

Read earlier posts about dismantling the National Fossil Halls, and view the work in real time or time lapse via a webcam mounted in the main hall.

11/24/2014

The new exhibition, Last American Dinosaurs: Discovering a Lost World, opens tomorrow, November 25th. Our giant skeletons of Triceratops and Tyrannosaurus rex have been joined by dozens of smaller animal and plant specimens found in rocks of the Hell Creek Formation, which date from the very end of the Cretaceous Period, 66 million years ago. Exhibit labels and graphics have been installed, videos from the field are playing, and several artist's reconstructions of latest Cretaceous animals and their environments are on the walls. This series of photos shows the exhibit coming together over the last couple of weeks. Our Paleobiology and Exhibits staff have been busy!

Moving this heavy skull of Triceratops into place required a mechanical lift and strong arms. Piles of removable blocking were used to lower the skull, step-wise, into its final position.

Skeletons of a giant, flightless moa and a dodo were installed in the exhibit's section on modern extinctions. Coaxing a large piece of plexiglas into place was a job for four.

The bracket holding the lizard-like Polyglyphanodon in place gets an adjustment before its cover goes on.

Installing a touchable specimen, an exact replica of a dinosaur skin impression that we hold in our collections.

Covering turtle #1...

and installing turtle #2.

FossiLab gets its graphics. The shadow above the lab window is cast by the well-lit T. rex.

This large mural represents the ecosystem and environment inhabited by the dinosaurs displayed in the exhibit. A video nearby explores how scientists and artists collaborate to create scientifically accurate reconstructions of extinct organisms and ancient environments. The fossils of some of the small animals and plants represented in the mural are mounted in front.

Department of Paleobiology artist, Mary Parrish, right, created the paintings enlarged to cover nearly a full wall of the exhibit. Eleonore Dixon-Roche, left, made pen and ink reconstructions of some of the smaller animals.

The exhibit includes newly-cast bronze replicas of these Triceratops models created by Charles R. Knight in the late 1800's and Charles W. Gilmore in the early 20th Century, and of a modern reconstruction.

To read earlier posts about our work in the field and in the Museum to get ready for the exhibit, click here. Read more about the Hell Creek Formation in this post on the Museum's blog, Natural History Unearthed.

11/03/2014

When the National Fossil Halls closed in April, 2014 for renovation, we faced the enormous job of removing our many specimens from display. Throughout the Halls, we have opened and emptied display cases of small fossils, and now we are working to remove the bigger specimens. The work follows roughly the same pattern in each Hall. First, anything light enough to be hand carried is taken away. Then, a demolition crew dismantles railings and the raised flooring that passes between the exhibits. To remove the larger specimens, we have two choices. If they are small enough to fit through doorways and into freight elevators and strong enough to withstand some vibration, we roll them away intact. If they aren't, we take them apart and remove them from exhibit in pieces. Here are photos of specimen removal from the Ice Ages Hall, which took place during September and October.

Matthew Miller and Steve Jabo lift the heavy skull and antlers of a Late Pleistocene moose (Alces alces) from its exhibit bracket in the Ice Ages Hall.

Unlike larger mounts, this complete skeleton of an extinct four-horned pronghorn, Stockoceros onusrosagris, could be carried off exhibit without being dismantled first.

Decades ago, whoever mounted the tank-like Glyptotherium arizonae had the foresight to place it on a wheeled base. Once nearby exhibit flooring was cut away, moving the fossil was easy.

We took the heavy protective cover off the mummified bison (Bison crassicornis) just long enough to lift it off the raised exhibit platform and lower it onto a large dolly.

The bison and Glyptotherium are now safe in storage. We will conserve them and place them on new bases before installing them in the renovated exhibit.

One of our two giant ground sloths (Eremotherium rusconii) appears to peak over the temporary wooden barriers we built to protect the fossils from demolition work on nearby railings and raised flooring.

Before we dismantled the largest mounts, the Smithsonian's Digitization Program Office scanned them with a laser to create 3D images. Here, Jon Blundell scans the second giant ground sloth.

Not yet fully dismantled, the ground sloth's back ends stand at attention in the nearly-empty exhibit hall, with packing crates full of bones arrayed in front.

The ground sloths, the mastodon, and the mammoth, shown here, were carefully disassembled by the firm that will remount them for exhibit in the renovated Fossil Halls.

Packing the mammoth skull for shipment. The tusks have been removed and the skull rests upside down, revealing the two ridged teeth of the upper jaw and the heavy metal armature that held the skull in place on the mount.

Our Harlan's ground sloth, Paramylodon harlani, is the last intact mount in the Ice Ages Hall. Soon, this specimen will be taken apart and placed in archival storage where it will be preserved for scientific research and, perhaps, use in a future exhibit.

Photos by Abby Telfer.

Read earlier posts about dismantling the National Fossil Halls, and visit the Smithsonian 3D Digitization program website to view a scan of the mammoth that was made before it was dismantled.